Low temperature carbonization of coal



Aug 7, 1934- s. 15. MILLER 1,969,472 I LOW TEMPERATURE GARBONIZATION 0F COAL v Filed July 19, 1930 4 Sheets-Sheet l E s e g EL ATTORNEYS 4 Sheets-Sheet 2 ATTORNEYS Aug. 7, 1934. s. P. MILLER LOW TEMPERATURE CARBONIZATION OF COAL Filed July 19, 195o Aug. 7, 1934. s, P. MILLER LOW TEMPERATURE CARBONIZATION OF COAL 4 Sheets-Shet I5 Filed July 19, 1930 INVENTOR 5. PM BY za;

ATTORNEY 4 Sheets-Sheet 4 for INVENTOR XM M 6%@ ATTORNEYS Patented Aug. 7, 1934 i 1,969,472 LOW TEMPERATUIE CARBONIZATION OF Stuart Parmelee Miller, Englewood, N. J., assigner to The Barrett Company,iN ew York, N. Y., a corporation of New Jersey f Applicatie July 19, 1990, serial No. 469,039

' 3 claims. (c1. 2oz-30e) This invention relates to'low'temperature carbonization of coal by direct contact between the coal and hot foul coal distillation gases. The heat of the coal distillation gases is used to carbonize '.5 the coal. The invention includes boththerprocess and apparatus for carrying it out.

According to 'this invention hot coal distillatio-n gases which maybe ,collected'from a number of cokeovens orgas retorts are broughtinto direct contact with coal While the gases vare .still at a temperature sufliciently high to Icarbonize the coal and produce coke therefrom. The Word coke as used in this application includes semicoke or high volatile coke, the char produced from non-coking coals. The coal vdistillation gases used to effect the ylovv temperature carbonizationand produce coke are high temperature distillation gases and ".hot coal distillation gases as used herein refers to `hot foul high temperature distillation gases such as coke 'oven gases Vor gas retort .gases and does not include Vlovv temperature gases which are vnot sufliciently hot to effect low temperature distillation.

Coke ovens are operated ata ytemperature up to about 1000-1200 C., and are especially suitable i-or furnishing hot gases for Ycarrying out this invention. .Low Atemperature carbonization of coal is carried on .at lower temperatures, for example at temperatures of 1450 to 700 C., and

a high yield of distillate of rcharacteristic Aproperties is obtained as well vas a coke residue which may be a high volatile coke or semi-coke'or char. The temperature at which the low temperature carbonization is carried out is sufficiently lower than the temperature at which by-product-coke ovens are operated to make advantageous the use of hot foul by-product coke zovenggases -as :a :source of heat for carrying on low temperature carbonization.

40 The temperature, composition and rateof evolution of the gases coming from a vsingle-coke oven or vgas retort varies during the cooking-of a charge or coal in the oven. On collecti-ng `the gases from a number of ovens charged in rotation in an 'insulated header vor collecting main,

a gas 4stream of substantially uniformtemperwture, composition and :amount isobtained. `Elly properly insulating the header or main thegases may beccnveyed to the lou/"temperature .car-

bonizing apparatus at a -temperature'only slightly lower than the mean temperature atl which the gases leave 'the ovens.H By collecting in the Vhot gas header only gases from a` selected portion o! vthe coking cycle, the temperature of the gases .55 employed in the carboni'zing operation can be regulated. By selecting the gases from only the hottest portion of `the coking cycle, for example, the temperature of the gases employed will be abovethe mean temperature of the total combined gases from a number kof ovens. 'The yovens 60. `connected with the hot header or other collect ing means for conveying the gases to the low temperature retort are preferably also connected with `a collector main of the usual -type land by manipulation of valve means connecting the ovens Q5, with the header and with the usual `collector main, the gases from only a selected portion of Ythe icoking cycle may besent thru the header -to the carbonizing apparatus and when `the :carbonizing apparatus is not vinnuse the gases from 'lf-Q the entire coking cycle may be collected in the usual collector main. Hotfoul coal distillation gases comprise vcon-- densable constituents including light oils, .medium and heavy -oils and also heavy and greasy T5 'constitutents landin addition, entrained particles of coke, dust and pitch. -When coal is brought into direct contact with the hot gases in order to feffect its carbonization, the Vgasesare cooled, condensable constituents `are condensed, and vsuch .condensed materials together-With lmoreor-less of the entrained impurities may separate from the gases on vto the coal. 'Ih'e degree to whichthe `gases are cooled and to which condensable contituents are separated, depends upon the initial 85, temperature of the hot gases, the amount of' contained condensables and the amount and temper- ,ature of the coal brought in contact with unit :quantity Aof gas. The Water content of the coal `also affects vthe extent of the cooling of the .gas 9.0

:and of the condensation of oils, etc. The permanent gases, such as hydrogen, methane, etc., .contained :in the `hot coal distillation-gases to,- gether with oils not condensed and -suspended material not removed by lcontact with thefcoal will .pass thru the low temperature carbonizing retort and blendwith the gases and vapors generated-in this retort, and 'on subsequent cooling .a combined tar will be obtained Which-comprises bothprimary tar and constituents. ordinarily present -in cokeoven tar; -The resulting gasesmaybe further treated for the vrecovery ofA ammonia, light oils, /etc.., .The resulting,permanentgases l:may be sold as fuelgxeither alone or ,blended Withcoke oven gas, producer gas-or Water gas, etc. The vv gases may I:be used-rat least in g-part, for heatingl the coke ovens or .gas retorts Vin ,which the hot coal' distillation gases 'farei-generated, although,` due to-their highcaloricvalue, theymay rbe sold as fuel gas. 'v 1 *I 1- f' f -f' no `to substantially detar the 'the entering gases.

in a hot pitch scrubber of the type which con-- tains a small body of pitch and in which a rapidly rotating roll or otherelement of generally cylindrical contour dipping into the body of pitch is rotated at high speed to spray the gasesy passing thru the 'scrubber'. ,In a scrubber of this.

type a iine intense spray of the pitch sui'cient gases may be maintained. f f

The coal to be carbonized at low temperature` may be of any suitable size depending upon the method to be employed. Crushed or pulverized coal may be used to advantage since with a coal of this size a large surface of the coal is exposed tothe heating action-of' the gases and the coal may therefore be rapidly heated throughout and the low' temperature carbonization carried out relatively vrapidly and' a uniform product obtained. While lignite, brown coal and Illinois non-coking coals are particularly well adapted to carbonization at low temperature by coke oven gases, nevertheless bituminous coals Vin general mayreadily be carbonized.

l' f Various types of apparatus have been employed `for low temperature carbonization of coal. VCertain types of apparatus `are particularly adapted for handling certain coals, i. e. coals of high or low volatile content, etc. v`'Ihe coal may be showered down a tower counter-current to a stream of hot coal distillation gases which are passed up the tower. As the coal passes down thru the tower it comes into contact with gases of gradually increasing temperature and its temperature is raised, and with a tower 'ofsuiiicient height the temperature at which the fsemi-coke or coke leaves the bottom of the tower may be only slightly less than the temperature of The coal may be added to the-'top of a tower up through which hot coal distillation'gases are passing and the coal may accumulate in the tower 4and build up a charge of coal within the tower to 'be heated. Ihe rate at which the gases traverse -the'tower and the rate at which coal is fed to the vtower are so regulated that the coal` undergoes the desired heat-treatment within the tower. The coke produced may be discharged fromthe ybottomof the tower at a rate commensurate .with

the rate at which the coal is added to the top of "the tower. Y

h'ering' excessively to the wallsofthe retort.

Anysuitable'type' of horizontal or inclined retort may 'be' employed and-the'gases vmaypass lthru the 'retort in -a'direction countercurrent or c'cmfcurrentwith'the flow'of the coalorrcoke thru the retort.y Concurrent flow ofthe solid material -"afidfhot"gaseshas the advantage thatv it lessens the condensation of 'tar'o'r oils from thehot gases by contact with colder fuel in the retort. With concurrent ow. of fuelsandgases theentering fuelis brought into direct contact with .the hot..-

test gases and the semi-coke resulting from the low temperature carbonization is discharged from the retort at substantially the temperature at which the distillation gases leave the retort, which is suificienly high to carry with it desired vapors including` vapors, from the low temperature car-V bonizationand also vapors present in the hot coal distillation gases as they enter the carbonization retort'.

"f Countercurrent ow of solid material and gases, on the other hand, has the advantage that the coal reaches' a higher maximum temperature in the retort since it leaves the reto-rt in contact with the'hottest gases. With countercurrent iiow the coal on enteringthe retort comes in contact with gases that have already been partially cooled by Contact with coal, and as the coal passes thru `the retort it is brought into contact with gases of progressively higher temperatures. The coal after being preheated in this manner then comes `into contact with thegases entering the retort, which are at their maximum temperature.

The coal may be conveyed thru ai horizontal: or inclined retort by worms or. chains, or rakes or bars, or other suitable means.

In a vertical reto-rt thecoal may be carriedup thru the'retortl by means of a helix attached to a rotating-,shaft or cylinder. The gases may pass down thrusuch a retort inv which case-the gases and coal ilow in a 'countercurrent direction. WhereV concurrent ow o-fLthe gases-and fuel is desired the gases may be passed up thru the -retort. The carbonization may .beconducted in equipment such as the Plassmann retort inwhich the coal is held in relatively thin vlayers between lstationary metal plates. Hot gases are forced thru the coal to accomplish carbo-nization.

on the kind of `coal employed. .The preheated coal'may be then fed to a secondary retortof any of the types named and subjected to low temperature Ycarbonization therein.

' When vthe coal brought into direct contact with the hot coal distillation Vgases is'pulverized coal the gases Aleavingthe retort may be passedthru a centrifugal separator' or. other gas cleaning means to` remove entrained'particles of the coal fromvthe gases before they enter the; condensing system. Y The heat which is made available, according to the present invention,`for usefulv purposes'will be'appre'ci'ated from the fact that in an ordinary coke oven plant containing sixty. ovens; each 'charged with'fteen tons of coal, and'carrying out the cokingl operation 'over a period of eighteen hours, there Vvwill beA produced from each oven approximately 650,000 cubic feet ofgas at about 600 C; during thevcoking period, or there. will be continuously produced from the sixty ovens around 39,000,000 cubic feetof gas atatemperature .around 600i C. or higher in eighteen hours. Such a `volume of gases at such temperature will contain upward of around.815,000 B. t. u. per minute available above 150 C., or around 570,000 B, t. u.

vper, mimltgavalable abOY- 300 C.

With countercurrent flow of Yhotgas and coal in a. continuous low-temperature carbonization :retort,1.practica1ly all the heatmade Aavailable by the temperaturedrop, less radiation losses, may :be utilized effectingthe carbonization of the 'retort charge. In cases where the carbonization requires a gross heat in-putof 800:13. t. u., per vpound-.of coal, and where Vtheheat loss by radia- .tion '.isy 20%,.34,000'pounds of coal. may be car- -bonized-per hour, the :gases issuing from the retort; at about 300 C.

The temperature at which. the hotl 'gases leave Sthe. retort will determine thetype of tar' recov- .eredfrom them. Gases leaving at say; 309 C.,

will, on cooling, deposit a tar containing a rconsiderable Irange of high Vboiling oils, resins,

greases,.etc While vgasesY leaving at aL lower temperature, say, 150 .C.,.Will contain much less of such constituents.

Tar and pitch constituents produced both in the coke ovens or other high temperature coal distillation units,v and in the low temperature earbonization'retort are carried bythe gas and gradually depositedcas the gas cools. Such constituents Vas'these which are not carried out of the retort by the gases are eventually carbonized in admixturewith the retortl coal charge.

The invention will be further described in the accompanying drawings in connection with various types of equipment `employed* in combination with a coke oven battery, but it is intended and isito-be understood that it is notllimited -is preheated in the` rst stagefand carbonizedin the second stage. Y

`In the drawings,.5 isa coke oven battery. The collector main -6 connects with I the individual .ovensof the battery. thru the uptake pipes '1. A

cross-over main 8 connects the collector main Withcondensers, etc. This vapparatus may beof the usualty-pe and is shown moreor lessschematically in the drawings. Y

At the opposite side of the cokeoven block isa hot gas header .10. It is heavily insulated as .shown Vat 11. .Thehot .gas header is built insections with cleanout doors .12 for scrapingvv and cleaningcut .the hot gas vheader when required; The hot gasheader leads intothe rotating retort 13. Theretort islslowly rotatedthru suitable driving gears by'themotor 14. Thegasesenter .the retort from the hot gas header-thru the coke discharging. chamber 15. 'I'his chamber is sealed to the retort 13 by means of the stuiing boxj16. Low temperature. coke produced in the `retort 13 is discharged' thru this chamber l5 thru'the leg Y17 and quenching tank 17' into the bin 18. rl'he rotating gates 19 retain a portion of the finished coke in the leg 17 Where it is cooled. l'The bottom ofleg'i'?A isv sealed in the quenching water in A pipe 20 enters the' head 21 on the upper end coalzis charged tof theretort thrul this .pipe from the; hopper ZZand'thegases and vapors escape .thru this pipe'tothe condensers 23. Beyond the .condensers is an exhauster 24 for drawingthe gases. etc.- thru the system. Y

The condensers rnayfb'e. vof any. desired type. Direct 'condensers or indirect condensers may be employed. Fractionating condensers may be employed to collect desireddistillate fractions. In ,thei drawings 'ordinary direct condensers are employed. The condensatel and Water or ammonia liquor used for cooling the gases vare 'drawnoi into the decanter25. Froml thev decanter the ammonia liquorrand tar areseparately .collected inthe tanks 26: and 27. Y in passing thru the retort 13 the hot coke ove gases from the header 10. produced `by the distillation of coal are brought into Adirect contact with coal from the hopper 22. The hot gases and coal pass thru the retort in a countercurrent direction. The hot incoming gases are lbroughtinto direct Contact with the coke being discharged thru 15. The partially cooled gases leaving'the-retort thruv themain 20 come into contact Withv the coal entering the' retort. The gases leaving the retort `are cooled to a temperature somewhat above that of the incoming coal. VSuch countercurrent `flow of the coal and gases iseconomical from a heat standpoint. Some tar Will b e condensed from the coke oven gases and separate onlithe coal inthe retort' 12, especially in the cold vend .of the retort at which the coal enters. This tar maybe distilled to pitch and then to coke. This coke will adhere to the coke produced bythe 10W temperature carbonization of the coaland will be 'discharged with `this coke thru the 'discharge legV 17 intoithe -bin 18. The tar collected in thei tank 27 yis a 'combined tar comprising vconstituents condensed from the coke oven gases and constituents distilled from the tar during the lowtemperature -carbonizing process. kConcurrent ow of the coal Aand vgases may be employed where preferred.

4lin Figs. -5 and l6 apparatus is shown in which the coal'and hot gases pass thru the 10W temperature'carbonizing retort in a concurrent direction. 120

lli-Iotl coke oven gases from .selected ovens of :the battery 5a in which coal is distilled are collected .in the hot gas header 10a. AThe hot gases from this header enter the retort 40v inwhichthey are ,-broughtxinto direct contact with coal admitted tothe retortfrom thehopperll. IIn the retort is van oscillating arm 42v driven by the, oscillating apparatus 44 which may beof any suitable-type well knownr in the art. On theoscillating member 42areagitating arms 45. These are oscillated Within the retort keeping the coalin'motion and 4agitatingv and stirring the coal rand semi-coke or vcoke within the retort toprevent its adhering to the .walls of the retort and becoming'coked on ythese Walls. The agitating arms.45 `are provided with suitable shoes 46 for scraping the bottom vof the retort. 'Scrapers 47 arearranged in the upper portion of the retort to remove any material -whichmay adhere to the arms and shoes 45 and46.' g

v.The coke is discharged from theretort thru the dischargelegz. -It is quenched VVand then :collected in the bin 51. The hot. gases and `vapors Ypass `from the retort into the condenser 52. 'An eirhausterv is shown at 53. f' .Thezhot coke vovenfgases7 as they enter the retort `-iOirom thehot gas header 10a come in contact with fresh coal discharged from the hop- -per 41. :The coal is agitated in an atmosphere of the hot gasesl in the retorty40 `and is heated, and 50 l io Ytillation chamber 61.

on further 4heating becomes plastic and finally forms semi-coke or coke. The retort 40 isl provided with suitable agitating means tojprevent any undue adhesion vof plastic materialto the walls of the retort. On further heating the material being colred` passes 4from the plastic stage tosemi-cokefor coke.' The coke produced in a'still of this type iin which the material'is subjected to constantv agitation during'the coking operation is more or less .lumpy or'granular, the pieces not being smalL In general the'gases will leave the retort 40 at a higher temperature than when countercurrent flow is employed, and the `coke made will, therefore, contain less of the products derived from condensate from lthev coke oven gases. Coalrrnayv alsobe carbonized by countercurrent flow of the coal and the hot gases in this type of retort. .l

The third modication of apparauts shown in the drawings provides means for a two-stage carbonizing process. Two towers are arranged one above the other. .'In the upper tower 6c, which `may be termed the primary distillation chamber,

the coal Ais preheated and'dried. In the `lower tower 61 the f preheatedY and partially distilled coal is carbonized and coke is produced. Hot coke oven gases from selected ovens of the battery 5b wherein coalvis being distilled are collected in the hot gas header. b. A 'small portion of'these gases isfsupplied thruw'the line 62 into the-bottom` ofA the primary' distillation chamber v60.1-Iot coke ovenrgases are admitted to the'bcttom of this tower in ay quantity suiii'cientto raise the temperature ofthe coal to, for exarnple,l300 or 325 C. Sonie'tar separates from the gases Ain the Lupper portion of the tower and this ymay be distilled to pitch of high melting point by the incoming gases in the lower portion of the tower or.v in thetower 61;vv v

. f A hopper 63 is provided above the tower 6D to supply coal to the primary distillation chamber and this coal is preferably pulverized. The'po'wdered coal falls in a shower thru thevascending hot gases, by which it is heated to' effect drying and preliminary distillation." Ther-top of the Vchan'riber e'isenlargeda's shown at '64; to provide for-reducing the velocitylof the gases as they es; cape from the tower to allow'coal-'particles carried'by'the gases 'to settle out of' the gases back into the tower. Thegases and vapors leaving the vtower pass to afcv'ondenser 65 inwhichcoke oven tar constituents arel separated ironrthe gases. This condenser may bethe 'same condenseras that employed for cooling the balance ofthe' coke oven gases fromthe battery 5i) which are lnot collected in the hot gasv header 1Gb. An'exhauster 66- is provided for drawing the gases ythru the system.

kA directA condenser is 'shown at 65 and separate means 67 'and 68 are provided for separately drawing ofi ammonia liquor and tar from-the de- 'The coal preheatedrin theprimary distillation chamber 60' isdischarged into the secondary dis- Hot coke oven gases sup'- plied from the hot gas header 10b thru the main 69 enter the bottom oi' this chamber and carbonizethe preheated coal lby direct contact'as 'it falls thruthe ascending hot gas stream. The

' coke produced is discharged to the sealed storage bin '70. The h ot gases andV vapors resulting from the coal carbonization' .process pass frornjthe chamberf 61 thru the main 7l to condensersr72.

'Theseconde'nser's may be of any ordinaryY type.

Direct `cer'idens'ers are shown. Fractional'ondensers may be'employed where desired. -AneX'- the decanters and 76, respectively. ',Chamber 60 or 61 or both'may be provided-with agitating or scrapingmeans.

Ordinary low temperature carbonization plants are'expensive to-install since theyinclude agas producer or other source of fuel gas'and they are expensive .to operate because of the 4heat required. However,-wl1e'nA ta rlow temperaturey re` tortis operated in combination with a coke oven battery or gas retort plant in which thewaste heat Vof the `freshhot coal distillation gases is utilized vfor carbonizing the coal, asdescribed and claimed herein, there is no necessity fora gas producer or other fuelgas plant for Vproducing gases to be burned to provide theheat vrequired viny thek low temperature" carboni'zing alpparatus. The apparatusemployed for the recovery of ammonia and light oils employedfor treating the high temperature distillation gases may be used to treat the low temperature 'carbonizah tion gases. The cost of installing allow tempera'- ture carbonization plant in vrcombination withta coke oveny plant'or gas'retort plant and the cost o operating such a plant in combinationvwith 'a coke oven plant or gaspla'nt may thus be -materially'less than the constructionl and operation of a low temperature carbonization plant at -a point wherev foul hot coald-istillation gases are not available. The type of low temperature carbonization apparatus employed may be selected withga view` to preparing'coke or s'emi-cok'e-or gas required to meet any-particular needs'. i

vl. The method'of carbonizing coal and producing a blended highandlow-temperature-ca bo'nization tar'product at a coke oven plant, which comprises effecting vhigh temperature carbon'iz'ation of coal 'in coke ovensofA the;planttlfierdebyl producing coke and hot coal carbonization gases containing Y, high-temperature-tary yfconstiinifelnts, bringingy the hot fresh coal carbonization' gases into directcontact lwith coal sofas to eiect low temperature carbonization of the coal by the sen'- sible heat contained inthe 'coal"carbonization gasesl and produce low-temperaturetar constituents therefrom, A drawing 01T' the `'resultant gases and vapors comprising high-: `and low-temperature-'tar constituents and coolingjthem to recover a v blended tar' product j comprising constituents rresulting from the high temperature carboniza- 'ion of coal and, constituentsresulting' from theY low temperature carboniration` of coal; f 2. ,The method of." operating aV coke oven plant for the production `o f a blended highftemperaf ture-'tar and'l low-temperature-tar product,fwhic h comprises eiecting thelhigh temperature carboninterna-l fleeting thef resultant' gases containing' hightemperature-tar constituents'ffrom va portio'ngA of the ovens of Athe plantLfbringingthe hotV fresh" coal carbonizationgases into direct 'contact'-wit'h lcoal Y so as to effect the low-temperature carbonizaf tion of coal by the sensible heat containedqirrfthp coaldistillation gases; drawing :01T the resultant gases `and vapors comprising highfandlow-.ternf primary distillation chamber, means for bringing hot coke oven gases from the battery into direct contact With the coal in the primary distiilation chamber to preheat the coal, means for discharging the preheated coal to the secondary distillation chamber, means for bringing the preheated coal into direct contact with hotV coke Y oven gases from the battery in the secondary distillation chamber, and a condenser for cooling the gases and vapors leaving the secondary distillation chamber.

S. P. MILLER. 

